Modern digital oscilloscopes all include a data acquisition storage module, which is controlled by triggers and timebase. In general, the control principle is as follows: the ADC (analog-to-digital converter) and acquisition memory start to work when the oscilloscope is in data acquiring mode, the voltage signals from oscilloscope probes are converted into binary data by the ADC, and then the data is stored into the acquisition memory; the sampling frequency of the ADC is determined by timebase and depth of the acquisition memory; the oscilloscope determines when to start and when to stop saving the acquired data base on trigger time and timebase; when the acquisition memory stops the savage, the data saved in the storage is the data to be processed by the oscilloscope; then the data processor reads the data from the acquisition memory and processes the data; after all the data in the acquisition memory is read out, the acquisition memory begins a next data savage and repeats this cycle again and again.
The operation mode of traditional data acquisition memory can be single segmental storage or multi-segmental storage. In single segmental storage mode, the data acquiring module acquires data continually, and the procedure of writing data into acquisition memory is control by the trigger signal generating timing and the timebase setting; the data read-out module reads the data out from the acquisition memory and provides it to the subsequent data processing module to process. During the data read-out procedure, the data cannot be written into acquisition memory. Accordingly, the oscilloscope will have a “dead-time”, during the “dead-time” period, the oscilloscope cannot record any data acquired.
In multi-segmental storage mode, a relatively larger buffer is divided into multiple small acquisition memories, each small acquisition memory records one segment of waveform data Each small acquisition memory work similar to single segmental storage memory, but in multi segmental storage mode, the acquisition memories can operate alternately, namely when one acquisition memory stops writing data, the data can be wrote into another acquisition memory. This multi-segmental storage mode can reduce dead-time effectively, however it fails to achieve seamless acquisition. Because each acquisition memory can only record one data segment, the beginning and ending of one data segment is actually controlled by trigger signals, if the time intervals between the trigger signals equal to storage time of acquisition memories, the data is just seamlessly stored in adjacent acquisition memories, however, in real situation, the time intervals between the trigger signals are uncertain, accordingly, adjacent waveform segments are not seamlessly continuous.
Additionally, in prior art, in the single segmental storage mode or multi-segmental storage mode, since each trigger event corresponds to one segment of acquisition memory, for a given sampling frequency, the shorter the trigger interval is, the shorter the acquisition memory is, that is, the shallower the memory depth is, therefore, the higher the capture rate is, the shorter the data segment is. The capture rate and the memory depth are mutual-restrained, and hence it cannot achieve the maxis rapture rate and the maximum memory depth simultaneously.